Spark plug



July 28, 1925. 1,547,918

' L. G. HOWARD SPARK PLUG- Filed Nov. 23, 1922 attain,

Patented July 28, 1925.

mirto STATES PATENT orifice.

LORENZO e. HOWARD, or rnovrnnivon, RHODE rsLANn.

SPARK PLUG.

Application filed November 23, 1922. Serial No. 602,795.

is minimized and wherein the disadvantages ordinarily resulting from the fracture of a core are neutralized by the provision of means for preventing detached portions of the core from dropping into the motor cylinders. Y Y

A further object of the invention is to provide a plurality kof selectively or interchangeably operative groundingelectrodes or elements which perform the additional function of reinforcing the insulating core and particularly that portion of said core which is directly exposed to the heat of the explosion chamber, and to so dispose these selectively or interchangeably operative grounding electrodes with relation to the main or positive electrode as lto the retainers to prevent possibly detached portions of the core from finding their way into the motor` cylinders.

A further object ofthe invention is to provide a simple, efficient and well protected f arrangement of indicatingv and intensifying spark gap which, while'literally available for inspection by the operator, is not subject to injury in the ordinary use and comparatively rough handling of commercial spark plugs.

With these and related objects in view, the invention consists in a construction and combination of parts of which a preferred embodiment is shown in the accompanying drawings, wherein:

Figure 1 is a longitudinal sectional view of the spark plug.

Figure 2 is a transverse view on the plane indicated by the line 2--2 of Figure 1.

Figure 3 is an inner end vie-w of the plug.

Fi ure L is a sectional view of the inner mem er of the core when constructed without reference to the accommodation of an intensifying spark gap.

The device consists of a shell 10, threaded as in the usual practice at 11 for engagement with the opening in the cylinder head and tted at its outer end with an inserted shell nut 12 having threaded engagement therewith. The shell is provided with an interior bearing shoulder 13 between which and the inner endV o-f the shell nut is arranged an vannular enlargement for theinsulating core which consists ,of separate inner and outer members 14 and A15, with which are associated the cushioning gaskets 16 andr 17.

An interlocking connection is established by the members of the core by providing .one of them as in the construction illustrated the inner member with an axial tongue 18 fitted in an axial `bore 19 of the the displacement of the inner core member which will be held seated subject to the removal of the grounding disk.

Extending axially through the plug is a main or positive electrode 23 serving to hold the core members in their proper relative positions by reason of a collar 24 bear-4 ing against the inner end of the inner core member and a nut 25 bearing against the outer end of the outer core member, and carried by the innercore member in a spaced relation lwith the main electrode are the grounding electrodes 26 which extend longitudinally through and in reinforcing relation to the inner core member with their exposed inner terminals inturned as indicated at 27 to provide suitable spark gaps for ignition purposes. These grounding electrodes are in connection electrically at their outer ends with the grounding disl 2O and in the construction illustrated are provided with terminal hooks or similar projections which engage the outer end of the inner core member in position to receive the pressure of the grounding disk which in turn is held in place by the outer core member, clamped by the action on the shell nut. This arrangement provides against the accidental turning of the grounding electrodes to displace their terminals 27 with relation to the main electrode.

When, as indicated in Figures l and 2, it is desired to employ an intensifying spark gap to serve also as a telltale or Yindicator for the information of the operator as to' the proper functioning of the battery or generator, the outer core member, instead of yheilig closed throughout as shown in Figure 4, is provided with ay transverse opening 28 to expose the separated terminals of sections of the main electrodel which, however, are connected by a cage 29 of suitable insulating material held in place by nuts 8O and 31.

The interposition of the spark gap which isthus visible through the slot 28 thus does not destroy the efhciency of the main electrode as a tierod for connecting the inner and outer members of the core and yet the extent of the gap between the terminals at the spark gap may be adjusted to produce the desired effect.

The collar 24 of the main electrode and the inwardly directed terminals of the grounding electrodes which are suitably anchored in and serve as reinforcing elements for the members of the core, serve to prevent an'ykdetached fragments of the core from dropping vaway from the vspark plugand thus falling into the cylinder of the motor, while the spaced arrangement of the core throughout its lengthwith reference to the inner surface of the shell and nut provides for differences in rates of expansion of the core and shell without placing an objectionable strain upon the former, while the cushioning of the core in the shell minimizes the tendency Vto fracture by vibration.

While the main electrode 23 is hereinaboveireferred to as serving to hold the core members in their proper' relative positions, and while as a matter of fact there is a reinforcing function performed by such electrode with reference to the core by reason of the fact that said electrode notwithstanding the interposition of the spark gap constitutes a continuous tensionable element eX- tending from one end of the sectional core to the other and having elements bearing upon the remote extremities thereof, it will be obvious from the foregoing description that the features of the construction which are relied upon mainly to hold the several members of the core in their proper positions with relation to the shell and each other are the grounding'disk 2O which locks the inner core member in place in theshell, and the shell nut 12 which locks the outer core member in its 'place in the shell, subject to certain and fully explained cushioning means which are vinterposed lbetween the parts'to prevent injurious jarring of the core members. f

It will further be understood that the outer core member which `is specifically illustrated in Figure 4 and which is not provided with an intensifying spark gap window opening or means of permitting inspection of the interior thereof may be substituted for the outer core member which is illustrated in Figures l and 2 when, lfor eX- amp'le, the inspection of the. spark gap is not deemed necessary, and when such modified form vof outer coreinember is'thus employed, due to the construction thereof as 'clearly vshown vin Figure 4, the 'spark gap feature of the main electrode'ma'y orma-y not be used at the option of the manufacturer.

`Hzwing described the invention, what is claimed as new and useful is :f

A spark plug comp-rising a shell, a nut vscrewed therein, a core composed of sections yhoused within the shell `and nut, one section Ihaving a central opening land the otherhavin/g a centrally located tongue which fits snugly in said opening, la grounding disk interposed between said core sections 'and 'having :an opening which `receives the `tongue and'having its peripheral portion yin contact with the shell, an electrode passing centrally through the core and `grounding electrodes passing through the Hinner `core section and 'having contact with the grounding disk, the inner end portions ofthe said electrodes extending tbeyond the inner end ofthe core and'b'e-ing spaced from each other. j j l 'In testimony whereof Yhe 'aiHiXes his signature. Y LORENZO G. HOWARD.. 

